This invention relates to wheel assemblies and more particularly to wheel assemblies especially adapted for use with large carts such as refuse carts.
With the ever increasing industrialization of our society, the need for a quick and efficient means of removing waste for ultimate disposal has steadily increased. The industry that has grown up to service this need has largely evolved in two directions. For relatively lighter and/or lower bulk waste disposal requirements, containers are provided at the user facility which, when filled with waste matter, are emptied into a refuse truck by a suitable hoisting mechanism and then replaced in position at the user facility to receive more refuse. In situations requiring larger volumes or heavier weights of refuse, the so-called "roll off" container or cart has been used. The roll off carts typically provide a capacity of between 12 and 40 cubic yards; may be used in association with an end compactor at the user facility; and are typically picked up and carried away when full on a custom vehicle, in piggyback style, with the vehicle carrying away the filled cart also delivering a new, empty cart to the user facility prior to pickup of the filled cart. These large refuse carts, in the course of loading and unloading onto the associated custom vehicle, receive considerable abuse. Since they must be dragged considerable distances both during the placement and the removal operations, they are typically provided with wheel assemblies at the four corners of the cart. The wheel assemblies sustain heavy abuse, not only because of the extremely heavy loads being carried in the carts, but also by virtue of the rough handling and the rough terrain over which the carts are dragged. The wheel assemblies in the past have generally comprised relatively standard designs in which a simple wheel is journalled on a hot rolled mild steel axle extending between parallel mounting plates on the corners of the cart. Due to the relatively unsophisticated design of the wheel assemblies and the extremely heavy abuse that the wheel assemblies receive, the wheel assemblies have become extremely high maintenance items. It is not unusual, for example, for the wheel assemblies to wear out to a point of being unusable in as short a time as three months. Typically the wheel assemblies are rebuilt, placed back in service, and then again rebuilt after which they again quickly wear out. A typical average total life of a wheel assembly, including several rebuilds, is about two years whereafter the entire wheel assembly must be replaced. In addition to the considerable expense associated with with rebuilding and ultimately replacing the wheel assemblies, the wheel assemblies may become dislodged during road transport on the associated vehicle and run wild and at high speed along the roadway, creating a potential for serious damage to other vehicles and/or personal injury. Further, since these containers are typically used in conjunction with an on site compactor, the cart can no longer be set at the proper height required for latching onto the compactor after it has lost a wheel assembly. Further, a container with a lost or severely damaged wheel assembly inflicts severe damage to the associated asphalt pavement onto which it is placed or over which it is dragged during the loading or unloading operation. Further, when a cart is taken out of service because of a damaged wheel assembly the cart must be brought into the main depot for maintenance and repair, resulting in time loss by the driver of the associated vehicle and revenue loss because the cart is out of service.
Various attempts have been made to introduce more sophistication into the wheel assemblies of these refuse carts in order to reduce the maintenance problem. For example, various attempts have been made to incorporate grease fittings so that lubrication can be added to the hub and axle assembly; other attempts have involved the use of roller or ball-type bearings in the wheel assemblies; and other attempts have involved the use of plastic or bronze bushings in the wheel assemblies. However, none of these attempts to improve the durability of the wheel assemblies has met with any degree of commercial success. Specifically, in the case of the lubricated wheel assemblies, the truck drivers are often remiss in greasing the axles on a regular schedule, the grease fittings become damaged and cannot be replenished with grease, or the grease fittings accumulate sand and dirt making it difficult or impossible to snap on the grease gun fitting or, even if greasing is possible, the greasing operation pumps in sand and dirt which in turn causes high abrasion failure of the axle and hub. In the case of the roller or ball-type bearing designs, it has been found that the extremely high gross vehicle weights and extremely high shock load forces encountered by these refuse carts causes immediate or eventual catastrophic failure to the internal bearing parts. In the case of the plastic or bronze bushing designs, the extremely high gross vehicle weights cause material flow-type deformation with resultant immediate or eventual failure of the wheel assembly.